Add Callback{,Option}.zip

Author: japgolly

core/src/main/scala/japgolly/scalajs/react/Callback.scala

@@ -239,6 +239,12 @@ final class CallbackTo[A] private[react] (private[CallbackTo] val f: () => A) ex
   @inline def <<[B](runBefore: CallbackTo[B]): CallbackTo[A] =
     runBefore >> this
 
+  def zip[B](cb: CallbackTo[B]): CallbackTo[(A, B)] =
+    for {
+      a <- this
+      b <- cb
+    } yield (a, b)
+
   /**
    * Discard the value produced by this callback.
    */

core/src/main/scala/japgolly/scalajs/react/CallbackOption.scala

@@ -166,6 +166,12 @@ final class CallbackOption[A](private val cbfn: () => Option[A]) extends AnyVal
       _ <- next
     } yield a
 
+  def zip[B](cb: CallbackOption[B]): CallbackOption[(A, B)] =
+    for {
+      a <- this
+      b <- cb
+    } yield (a, b)
+
   /**
    * Discard the value produced by this callback.
    */